The Alphabet of the English language and most of the European languages
The farthest known roots trace back to Proto-Sinaitic, 3800 years ago. It was mainly consonantal and was primarily based on the Egyptian hieroglyphics. From then on, small changes accumulated to give us what the alphabet looks like today. This interesting evolution was beautifully summarized in a poster that was drawn by Matt Baker and spotted by Colossal. Here is what it looks like:
The Alphabet started to gain the shape it has today in Archaic Greek, circa 750 BCE. Then, by 1BCE, the Romans standardized the scrolls into uniform sheets which resulted in the creation of the Latin alphabet. This means that our alphabet was largely done 2000 ago. Writing was simple and too rudimentary back then, it would reach its true potential after two more whole millennia. This would give rise to pieces of writing that would forever change the course of humanity, such as Constitutions, The Origin of Species, A Brief History of Time, etc. We can only imagine what lies ahead. So, using a handful of symbols that we wittingly created, we opened unlimited horizons in front of us.